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First description of Candida nivariensis in Brazil: antifungal susceptibility profile and potential virulence attributes
Figueiredo-Carvalho, Maria Helena Galdino; Ramos, Livia de Souza; Barbedo, Leonardo Silva; Chaves, Alessandra Leal da Silva; Muramoto, Ilda Akemi; Santos, André Luis Souza dos; Almeida-Paes, Rodrigo & Zancopé-Oliveira, Rosely Maria
Abstract
This study evaluated the antifungal susceptibility profile and the production of potential virulence attributes
in a clinical strain of Candida nivariensis for the first time in Brazil, as identified by sequencing the internal transcribed
spacer (ITS)1-5.8S-ITS2 region and D1/D2 domains of the 28S of the rDNA. For comparative purposes, tests
were also performed with reference strains. All strains presented low planktonic minimal inhibitory concentrations
(PMICs) to amphotericin B (AMB), caspofungin (CAS), and voriconazole. However, our strain showed elevated
planktonic MICs to posaconazole (POS) and itraconazole, in addition to fluconazole resistance. Adherence to inert
surfaces was conducted onto glass and polystyrene. The biofilm formation and antifungal susceptibility on biofilm-growing
cells were evaluated by crystal violet staining and a XTT reduction assay. All fungal strains were able to
bind both tested surfaces and form biofilm, with a binding preference to polystyrene (p < 0.001). AMB promoted
significant reductions (≈50%) in biofilm production by our C. nivariensis strain using both methodologies. This reduction
was also observed for CAS and POS, but only in the XTT assay. All strains were excellent protease producers
and moderate phytase producers, but lipases were not detected. This study reinforces the pathogenic potential of C.
nivariensis and its possible resistance profile to the azolic drugs generally used for candidiasis management.
Keywords
Candida nivariensis; Brazil; antifungal resistance; hydrolytic enzymes; adherence; biofilm
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